Atoms - Chapter Notes for Class 9 Science

Atoms are the basic building blocks of matter. In this chapter, we will learn about the structure of atoms, their various components, and their properties.

1. Introduction to Atoms
- Atoms are the smallest units of matter that cannot be divided further.
- They are composed of subatomic particles such as protons, neutrons, and electrons.
- Atoms combine to form molecules and compounds.

2. Structure of Atoms
- Atoms consist of a nucleus at the center, which contains protons and neutrons.
- Electrons orbit around the nucleus in specific energy levels or shells.
- The number of protons determines the atomic number and the identity of the element.

3. Subatomic Particles
- Protons are positively charged particles found in the nucleus.
- Neutrons are neutral particles also located in the nucleus.
- Electrons are negatively charged particles that revolve around the nucleus.

4. Atomic Mass and Isotopes
- Atomic mass is the sum of protons and neutrons in an atom.
- Isotopes are atoms of the same element with different numbers of neutrons.
- They have the same atomic number but different atomic masses.

5. Electronic Configuration
- Electrons are arranged in specific energy levels or shells.
- The first shell can hold a maximum of 2 electrons, while the second and third shells can hold up to 8 electrons each.
- The electronic configuration of an atom determines its chemical properties.

6. Valency and Chemical Bonding
- Valency is the combining capacity of an atom.
- Atoms gain, lose, or share electrons to achieve a stable electron configuration.
- Chemical bonding occurs when atoms combine to form molecules or compounds.

7. Atomic Number and Mass Number
- Atomic number represents the number of protons in an atom.
- Mass number is the sum of protons and neutrons.
- Isotopes have the same atomic number but different mass numbers.

8. Conclusion
- Atoms are the fundamental units of matter and play a crucial role in understanding the properties of elements and compounds.
- The structure of atoms and their arrangement of electrons determine their chemical behavior.

Animal Tissue - Complete Notes for Class 9 Science

Animal tissues are specialized groups of cells that perform specific functions in an animal's body. In this chapter, we will explore the different types of animal tissues and their functions.

1. Introduction to Animal Tissues
- Animal tissues are classified into four major types: epithelial, connective, muscular, and nervous tissues.
- Each type of tissue has unique characteristics and functions.

2. Epithelial Tissue
- Epithelial tissue covers the surfaces of the body, lines cavities, and forms glands.
- It provides protection, absorption, secretion, and excretion.

3. Connective Tissue
- Connective tissues provide support, protection, and attachment.
- They are made up of cells and an extracellular matrix.
- Examples include bone, cartilage, blood, and adipose tissue.

4. Muscular Tissue
- Muscular tissue is responsible for movement and locomotion.
- It is composed of

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